1. Field of the Invention.
The present invention relates to visible and ultraviolet lasers, and more particularly to visible and ultraviolet lasers based on excimer transitions in the diatomic homonuclear halogen molecules.
2. Description of the Prior Art.
The well-known molecular iodine (I.sub.2) ultraviolet laser at 342 nm arises from the D' (1.432, .sup.3 .pi..sub.2g) to A' (2431, .sup.3 .pi..sub.2u) transition of the I.sub.2 molecule. This laser has been pumped by both electron beam and optical excitation. The latter excitation is possible because the I.sub.2 absorption band centered near 190 nm results in the production of excited D.sup.1 .SIGMA..sub.u.sup.+ molecules. In the presence of a buffer gas these molecules collisionally relax to the lowest lying ion-pair state, D'.sup.3 .pi..sub.2g, which is the upper energy level for the ultraviolet laser. Both the spontaneous emission and laser spectra for the D' to A' band exhibit well-developed vibrational structure since the transition is bound to bound. Output energies up to 13 Joules from an optically pumped I.sub.2 laser have been reported. Such lasers are not tunable, and lase in a portion of the spectrum where others, more efficient lasers, such as ZeF, exist.